Pyruvic acid joins the pool of a muscle cell at 60 thousand molecules a minute…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Pyruvic acid joins the pool of a muscle cell at thousand molecules a minute. The cell uses per cent of the pool each minute. (a) At what pool size are the supply and the use equal? (b) What is the flow through the pathway when the pool has settled? (c) The supply doubles. What size does the pool settle at now? (d) Is the settled pool at equilibrium? Explain.
Need a reminder? The key ideaShow
Metabolism is all the chemical reactions of a living thing, in pathways of enzyme-catalysed steps. Anabolic pathways build molecules and use energy; catabolic pathways break them down and release energy, which is stored in ATP, the energy currency. Metabolic flux is the rate of flow through a pathway. A closed system reaches equilibrium: no net flow, no free energy and no work. A living cell is an open system held in a steady state far from equilibrium by a continuous flow of matter and energy.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The steady pool. The use is of the pool, and it must equal the supply of . So the pool is thousand molecules.
Step 2. The flow. What enters each minute also leaves, so the flow through the pathway is thousand molecules a minute.
Step 3. Double the supply. thousand molecules.
Step 4. Equilibrium. No. At equilibrium nothing flows. Here material flows through the pathway all the time, so the pool is in a steady state and the cell is an open system.
Answer: (a) thousand molecules; (b) thousand molecules a minute; (c) thousand molecules; (d) no, it is a steady state, not an equilibrium.
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